I stumbled upon this (probably simple) mathematical matrix I just couldn't solve. The problem is I came up with the answer 12 (which isn't one) and now I am so fixated on that that I am having trouble seeing other solutions :P. Can somebody solve it for me? The first image is the question, the second is the possible answers.
The answer is:
Any given diagonal contains the same number. You can get from one diagonal to the next by adding an incrementing number - +1, +2, +3 or +4 (1+1 → 2+2 → 4+3 → 7+4 → 11)
The solution is pretty simple.
All numbers stay the same in diagonals (obvious). To find numbers in the third column, we simply take the sum of the two other columns in a given row and the value of the cell in the row above in the first column. Thus, 2+4+7=13. :)
As Riley informed me... Its better to look at this as tribonacci numbers. In effect, we take the sum of each number in a row and that is equal to that of the third column in the row below...
Well, I guess the answer is
With 1, we get a symmetrical matrix, the symmetry is being formed by the main diagonal from top left to bottom right (1,4,1)